With the passage of the 2018 Agricultural Improvement Act or “Farm Bill,” hemp ‒ defined as cannabis and cannabis-derived products containing THC levels of 0.3% or less by dry weight, was removed from the federal definition of marijuana. With this change, hemp was also removed from Schedule I of the Controlled Substances Act (CSA). The result was a flood of hemp-derived CBD products, some claiming health and medical benefits, onto the consumer market.

However, the threshold of 0.3% THC in hemp products set by the Farm Bill has created a false impression to healthcare providers that there is evidence of the safety of this amount of THC. But the reality is there is not enough clinical data on THC safety thresholds to assess potential risks. In general, a level of about 1% THC is considered the threshold for cannabis to have a psychotropic or intoxicating effect.1 But the problem arises when more than 0.3% THC ends up in a product due to inconsistent production, quality testing and labeling.

Healthcare providers are often unaware of this lack of safety data as well as the inconsistencies in testing and labeling from state to state. In fact, a recent survey of more than 550 healthcare providers across neurology, physiatry, internal medicine and pediatrics published in Neurology Reviews found that more than half of responders believe the statement "0.3% THC has been clinically proven as safe" to be true.2 The truth is with the passage of the Farm Bill and the availability of CBD products online or in convenience stores, the U.S. Food and Drug Administration (FDA) and the Food, Drug and Cosmetic Act (FDCA) safeguards that healthcare providers and consumers rely upon effectively were side-stepped.

As former FDA Commissioner, Scott Gottlieb, M.D. noted at the time of the Farm Bill passage, “just as important … is what the law didn’t change: Congress explicitly preserved the (FDA’s) current authority to regulate products containing cannabis or cannabis-derived compounds under the Federal Food, Drug, and Cosmetic Act (FD&C Act) and section 351 of the Public Health Service Act. This allows the FDA to continue enforcing the law to protect patients and the public, while also providing potential regulatory pathways for products containing cannabis and cannabis-derived compounds.”3

The FDA has issued warnings and imposed fines on companies making misleading medical and health claims, but often it is healthcare providers who first learn of patients using CBD products and “adverse” events that may result. To ensure the FDA is aware and able to act to protect the public health, healthcare providers can report patient reported issues to the agency, much like they would for any other drug until a comprehensive federal framework for CBD oversight is put in place.

Until that time, the fact remains that products containing 0.3% or less of THC by dry weight can impair a person’s cognitive function, cause physical ailment and result in a positive drug test. The 0.3% or less by dry weight threshold is meaningless without comprehensive standards of total THC content by milligrams as well as oversight of the manufacturing and labeling process.

THC Percentage Infographic


1E. Small and D. Marcus, “Hemp: A New Crop with New Uses for North America,” in Trends in New Crops and New Uses, ed. J. Janick and A. Whipkey (Alexandria, VA: American Society for Horticultural Science Press, 2002).

2Neurology Reviews. Survey Identifies Gaps in Physician Knowledge About Cannabis and Cannabinoids. January 2020. https://www.neurologyreviews-digital.com/neurologyreviews/nord_march_2020/MobilePagedArticle.action?articleId=1566841#articleId1566841. Accessed July 20, 2020.

3U.S. Food and Drug Administration. Statement from FDA Commissioner Scott Gottlieb, M.D., on signing of the Agriculture Improvement Act and the agency’s regulation of products containing cannabis and cannabis-derived compounds. https://www.fda.gov/news-events/press-announcements/statement-fda-commissioner-scott-gottlieb-md-signing-agriculture-improvement-act-and-agencys. Accessed July 20, 2020.